Not applicable.
Not applicable.
The present invention relates generally to hand held calculators, and more particularly to a hand held pipe bending calculator that enables a workman to calculate offsets, saddles, and shrink.
Conventional linear slide rules and their annular cousins are well known. The devices generally comprise a mechanical devices having at least two numerical scales in movable relationship with one another so as to make a specific kind or kinds of calculations. Some early examples of calculators having an annular or disc shape include U.S. Pat. No. 697,861 to MacCollin, which teaches a mechanical calculator; U.S. Pat. No. 784,660 to Chritton, which teaches a lumber computer; U.S. Pat. No. 3,181,787 to Burns, which teaches a wall construction computer; U.S. Pat. No. 3,436,014 to Ochonicky, which teaches a heater calculator; and U.S. Pat. No. 3,716,015 to Godfrey, which teaches a measuring device to represent a value in metric and British length scales. These devices are specific to the function they perform and are not adapted for use in calculating pipe bends and lengths.
U.S. Pat. No. 3,199,777 to Martens teaches a disc computer used to calculate the data necessary for the proper bending of pipe, particularly the pipe used in cross country pipe lines. The device comprises three concentrically mounted discs in rotatable relation to one another, the middle disc being the largest and bearing scales on each of its faces. The outer discs carry scales on their outer faces which, when related to the scales on the middle disc, may be employed to calculate the total angle and twist angle of pipe when the horizontal angle and vertical angle are known. However, this device does not provide means to calculate shrink or take up of pipe resulting from bends made in the pipe.
U.S. Pat. No. 4,689,476 to Katz discloses a mariner""s dogleg course distance calculator. The calculator is a disc-shaped slide rule having a fixed base and an opaque slide element in sliding arrangement with respect to the fixed base. The base is provided with a scale of numbered indicia representative of rhumb line or direct course distances to the destination station. Underlying the slide element the base element is also provided with a table of numbered distance indicia comprising discrete running distances to be negotiated to the destination station at a number of dogleg or zig-zag course departure angles. The slide element of the calculator includes an array of windows, each of which represent a specific departure angle and which may be juxtaposed over the individual running distance indicia of the distance table of the fixed base so as to expose appropriate dogleg course distance information when the slide element is indexed to a specific rhumb line course distance displayed on the fixed base element. Each window of the slide element is also provided with reference indicia keying the specific departure angle represented thereby.
U.S. Pat. No. 4,308,451 to Shedlock teaches an overlap distance indicating device intended to allow a worker to determine the amount of overlap required to maintain lines of an angled section parallel and spaced throughout by a constant distance, from linear measurements of the slope or run of an angled section and the linear measurement of the rise of that angled section. The device comprises two fixed discs and two rotatable disc interposed between the two fixed discs. The rotatable disc has numerical indicia on one of the two surfaces that correspond to linear measurements of the run and slope of an angled section, and disposed on the other surface are indicia corresponding to linear measurements of overlapped distances. One of the two fixed discs has a window for exposing selected portions of the indicia corresponding to the slope and run of an angled section in correlation with adjacent indicia corresponding to the rise of an angled section. The other one of the two fixed discs has a window for exposing selected portions of the indicia corresponding to the overlap distances, in correlation with adjacent indicia which corresponds to the spacing distances between the lines of each section.
Finally, U.S. Pat. No. 5,691,523 to Calvo describes a machinery shaft alignment calculator for determining shimming requirements for a drive unit to be coupled with a driven unit in angular alignment. The circular slide rule device utilizes drive unit support separation data, coupling structure diameter, and measured angular offset values to determine shimming requirements for angular alignment of the drive and driven units, by shim addition or removal to the supports of the drive unit.
Of the known devices, none describes or teaches a hand held apparatus capable of calculating the angles for offset and saddle bends, and for calculating shrink or take up.
The present invention provides calculations directed and dedicated to workmen who install generally linear materials that must be bent for installation around other structures or for functional reasons, e.g., electrical conduit or plumbing pipe. The calculator comprises a lower circular disc and a concentric upper disc of smaller diameter in rotatable relationship to the lower disc. The upper disc includes a window through which may be viewed a numerical scale printed or impressed on the lower disc representing a continuous range of degrees of pipe or conduit bend that are commonly used in electrical conduit work (or any other applicable industry). The user simply dials in the degree of bend to be used and a first numerical scale at the perimeter of the upper disc aligns with a second numerical scale at the perimeter of the lower disc to show the relationship between the depth of pipe/conduit offset desired and the distance between bends.
The visual display provided by the present invention is similar to the display provided by well-known photographic light meters, but rather than showing a range of exposure combinations for f-stops and shutter-speeds based on user-selected luminance units of light, the pipe bending calculator of the present invention indicates the range of depth-of-offset/distance-between-bends combinations for a given bend in degrees.